Memory difference control of unknown unstable fixed points: Drifting parameter conditions and delayed measurement

Difference control schemes for controlling unstable fixed points become important if the exact position of the fixed point is unavailable or moving due to drifting parameters. We propose a memory difference control method for stabilization of a priori unknown unstable fixed points by introducing a memory term. If the amplitude of the control applied in the previous time step is added to the present control signal, fixed points with arbitrary Lyapunov numbers can be controlled. This method is also extended to compensate arbitrary time steps of measurement delay. We show that our method stabilizes orbits of the Chua circuit where ordinary difference control fails.Comment: 5 pages, 8 figures. See also chao-dyn/9810029 (Phys. Rev. E 70, 056225) and nlin.CD/0204031 (Phys. Rev. E 70, 046205

Andreev Probe of Persistent Current States in Superconducting Quantum Circuits

Using the extraordinary sensitivity of Andreev interferometers to the superconducting phase difference associated with currents, we measure the persistent current quantum states in superconducting loops interrupted by Josephson junctions. Straightforward electrical resistance measurements of the interferometers give continuous read-out of the states, allowing us to construct the energy spectrum of the quantum circuit. The probe is estimated to be more precise and faster than previous methods, and can measure the local phase difference in a wide range of superconducting circuits.Comment: Changes made in light of referees comments; to appear in PR

Accounting for Slow J/psi from B Decay

A slow J/psi excess exists in the inclusive B -> J/psi+X spectrum, and is indicative of some hadronic effect. From color octet nature of c cbar pair in b-> c cbar s decay, one such possibility would be B -> J/psi+ K_g decay, where K_g is a hybrid resonance with sbar g q constituents. We show that a K_g resonance of ~ 2 GeV mass and suitably broad width could be behind the excess.Comment: 4 pages, 2 figures. To appear in Phys. Rev.

Charmless Three-Body Baryonic B Decays

Motivated by recent data on B-> p pbar K decay, we study various charmless three-body baryonic B decay modes, including Lambda pbar pi, Sigma0 pbar pi, p pbar pi, p pbar Kbar0, in a factorization approach. These modes have rates of order 10^{-6}. There are two mechanisms for the baryon pair production, current-produced and transition. The behavior of decay spectra from these baryon production mechanisms can be understood by using QCD counting rules. Predictions on rates and decay spectra can be checked in the near future.Comment: 26 pages, 9 figures; version to appear in Phys. Rev.

Selective laser sintering of hydroxyapatite reinforced polyethylene composites for bioactive implants and tissue scaffold development

Selective laser sintering (SLS) has been investigated for the production of bioactive implants and tissue scaffolds using composites of high-density polyethylene (HDPE) reinforced with hydroxyapatite (HA) with the aim of achieving the rapid manufacturing of customized implants. Single-layer and multilayer block specimens made of HA-HDPE composites with 30 and 40 vol % HA were sintered successfully using a CO2 laser sintering system. Laser power and scanning speed had a significant effect on the sintering behaviour. The degree of particle fusion and porosity were influenced by the laser processing parameters, hence control can be attained by varying these parameters. Moreover, the SLS processing allowed exposure of HA particles on the surface of the composites and thereby should provide bioactive products. Pores existed in the SLS-fabricated composite parts and at certain processing parameters a significant fraction of the pores were within the optimal sizes for tissue regeneration. The results indicate that the SLS technique has the potential not only to fabricate HA-HDPE composite products but also to produce appropriate features for their application as bioactive implants and tissue scaffolds

Low-Mass Baryon-Antibaryon Enhancements in B Decays

The nature of low-mass baryon-antibaryon enhancements seen in B decays is explored. Three possibilities include (i) states near threshold as found in a model by Nambu and Jona-Lasinio, (ii) isoscalar states with $J^{PC} = 0^{\pm +}$ coupled to a pair of gluons, and (iii) low-mass enhancements favored by the fragmentation process. Ways of distinguishing these mechanisms using angular distributions and flavor symmetry are proposed.Comment: 8 pages, LaTeX, no figures, to be submitted to Phys. Rev. D. One reference adde

SU(3) and Nonet Breaking Effects in KL→γγK_L \to \gamma \gamma Induced by s→d+2gluons \to d + 2{gluon} due to Anomaly

In this paper we study the effects of $s\to d + 2{gluon}$ on $K_L \to \gamma\gamma$ in the Standard Model. We find that this interaction can induce new sizeable SU(3) and U(3) nonet breaking effects in $K_L - \eta, \eta'$ transitions and therefore in $K_L\to \gamma\gamma$ due to large matrix elements of $$ from QCD anomaly. These new effects play an important role in explaining the observed value. We also study the effects of this interaction on the contribution to $\Delta m_{K_L-K_S}$.Comment: RevTex, 12 Pages, no figures. Version to be published in PR

Hadronic B Decays to Charmed Baryons

We study exclusive B decays to final states containing a charmed baryon within the pole model framework. Since the strong coupling for $\Lambda_b\bar B N$ is larger than that for $\Sigma_b \bar BN$, the two-body charmful decay $B^-\to\Sigma_c^0\bar p$ has a rate larger than $\bar B^0\to\Lambda_c^+\bar p$ as the former proceeds via the $\Lambda_b$ pole while the latter via the $\Sigma_b$ pole. By the same token, the three-body decay $\bar B^0\to\Sigma_c^{++}\bar p\pi^-$ receives less baryon-pole contribution than $B^-\to\Lambda_c^+\bar p\pi^-$. However, because the important charmed-meson pole diagrams contribute constructively to the former and destructively to the latter, $\Sigma_c^{++}\bar p\pi^-$ has a rate slightly larger than $\Lambda_c^+\bar p\pi^-$. It is found that one quarter of the $B^-\to \Lambda_c^+\bar p\pi^-$ rate comes from the resonant contributions. We discuss the decays $\bar B^0\to\Sigma_c^0\bar p\pi^+$ and $B^-\to\Sigma_c^0\bar p\pi^0$ and stress that they are not color suppressed even though they can only proceed via an internal W emission.Comment: 25 pages, 6 figure

MRI brain scan study of minor physical anomalies to aid the early diagnosis of autism

Poster Sessionspublished_or_final_versionThe 27th International College of Neuropsychopharmacology Congress (CINP 2010), Hong Kong, China, 6-10 June 2010. In International Journal of Neuropsychopharmacology, 2010, v. 13, suppl. S1, p. 182, abstract no. P-14.03

Phenomenological Consequences of Right-handed Down Squark Mixings

The mixings of $d_R$ quarks, hidden from view in Standard Model (SM), are naturally the largest if one has an Abelian flavor symmetry. With supersymmetry (SUSY) their effects can surface via $\tilde d_R$ squark loops. Squark and gluino masses are at TeV scale, but they can still induce effects comparable to SM in $B_d$ (or $B_s$) mixings, while $D^0$ mixing could be close to recent hints from data. In general, CP phases would be different from SM, as may be indicated by recent B Factory data. Presence of non-standard soft SUSY breakings with large $\tan\beta$ could enhance $b\to d\gamma$ (or $s\gamma$) transitions.Comment: Version to appear in Phys. Rev. Let